Electronic/electrical circuitry is often operationally degraded due to the coupling of electrical noise through connectors which carry electrical signals to and from the circuitry. This degradation is partially due to the connector's susceptibility to external electromagnetic interference (EMI). Similarly, the lack of protection from electromagnetic interference allows the electrical signals to radiate outward from the connector assembly and contaminate the surrounding environment with EMI generated by the circuitry. The electrical signals may also be degraded due to environmental contamination (e.g., salt spray, corrosion, etc.) of the conductive electrical elements within the connector.
Various types of connectors are available to reduce these detrimental affects depending on the severity of the environment and the product usage for the particular connector (e.g., avionics, computers, automotive, etc.). Connectors typically used in avionics systems are often designed to meet the requirements put forth in the Department of Defense standard, MIL-C-38999. Connectors designed to this military standard can offer built-in protection against both EMI and environmental contamination. However, due to the size and expense of these connectors, there are situations where either space or weight is severely limited and thus these heavy duty connectors are not suitable or cost effective.
A connector widely used in the computer industry is the well known generic multipin "D" type electrical connector, which in the military market is built per the requirements of MIL-C-24308. "D" type connectors are relatively compact in both size and weight. However, the conventional "D" type connector does not incorporate the level of EMI and environmental protection offered by the MIL-C-38999 connector. In avionics systems (e.g., fighter/attack aircraft radars within a radome) conventional "D" type connectors are often external to a housing, and hence very susceptible to EMI coupling.
One alternative for reducing the EMI noise coupling and the resultant degradation of the signals in the "D" type connector, is to place analog filters within the electrical circuit receiving the signals. However, this can be expensive, prohibitively complex, and add too much weight and volume, particularly if each signal line from the connector requires analog filtering to attenuate the effects of the EMI signal degradation on the circuitry. Furthermore, filtering may not be a suitable alternative if the dominant noise from the EMI is at a low frequency, or within the frequency bandwidth of the signal carried within the connector.